EP0232918B1 - Optical waveguide glass fiber flame processing - Google Patents
Optical waveguide glass fiber flame processing Download PDFInfo
- Publication number
- EP0232918B1 EP0232918B1 EP87102086A EP87102086A EP0232918B1 EP 0232918 B1 EP0232918 B1 EP 0232918B1 EP 87102086 A EP87102086 A EP 87102086A EP 87102086 A EP87102086 A EP 87102086A EP 0232918 B1 EP0232918 B1 EP 0232918B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- optical waveguide
- silica
- flame
- flow
- flow portion
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/255—Splicing of light guides, e.g. by fusion or bonding
- G02B6/2551—Splicing of light guides, e.g. by fusion or bonding using thermal methods, e.g. fusion welding by arc discharge, laser beam, plasma torch
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B23/00—Re-forming shaped glass
- C03B23/04—Re-forming tubes or rods
- C03B23/043—Heating devices specially adapted for re-forming tubes or rods in general, e.g. burners
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B23/00—Re-forming shaped glass
- C03B23/20—Uniting glass pieces by fusing without substantial reshaping
- C03B23/207—Uniting glass rods, glass tubes, or hollow glassware
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/02—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor
- C03B37/025—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor from reheated softened tubes, rods, fibres or filaments, e.g. drawing fibres from preforms
- C03B37/027—Fibres composed of different sorts of glass, e.g. glass optical fibres
- C03B37/02736—Means for supporting, rotating or feeding the tubes, rods, fibres or filaments to be drawn, e.g. fibre draw towers, preform alignment, butt-joining preforms or dummy parts during feeding
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/10—Non-chemical treatment
- C03B37/14—Re-forming fibres or filaments, i.e. changing their shape
- C03B37/15—Re-forming fibres or filaments, i.e. changing their shape with heat application, e.g. for making optical fibres
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2205/00—Fibre drawing or extruding details
- C03B2205/30—Means for continuous drawing from a preform
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2205/00—Fibre drawing or extruding details
- C03B2205/60—Optical fibre draw furnaces
- C03B2205/62—Heating means for drawing
- C03B2205/68—Hot gas, e.g. plasma, flame, burner
Definitions
- the invention is concerned with optical waveguide glass fibers having low optical loss and high tensile strength as, e.g., in the case of fibers having a low-loss, high-strength splice connection.
- Optical waveguide glass fibers have become an increasingly important long-distance communications medium, and their commercial use for communications over intermediate and short distances is increasing as well.
- Manufacture of optical waveguide fibers typically is by drawing from a preform as may be made in a number of ways; in this respect see, e.g., U. S. Patent 4,217,027.
- drawn fibers typically are provided with a plastic coating, and coated fibers may be assembled into strands and cables.
- Heat fusion splicing typically involves the use of a torch producing a flame which results upon the combustion of gases such as, e.g., hydrogen or ammonia. And, of course, such a flame can be used for high-temperature processing for purposes other than splicing.
- flame processing can be used to facilitate drawing of a fiber to a smaller diameter, for side-by-side fusing of fibers as, e.g., in the manufacture of optical couplers and taps, as well as for the sake of modifying dopant profile. With respect to dopant profile modification see, e.g., J.T.
- EP-150 095 discloses flame processing with chlorine addition to result in highest tensile strength in a processed fiber, but there remain circumstances under which the use of chlorine is inadvisable, e.g., on the basis of safety or environmental considerations.
- the problem underlying the present invention is to provide for a method for making a glass fiber in accordance with the pre-characterizing part of claim 1 which is improved in regard of safety and environmental considerations.
- Resulting fibers have satisfactorily high tensile strength for most applications; for example, if processing is for the sake of fiber splicing, at least 80 percent of fibers spliced in accordance with the invention have a tensile strength greater than or equal to 3.45 GPa (500 kpsi).
- the Figure schematically illustrates a preferred embodiment of the invention, namely fiber splicing by heating of abutting fiber segment ends with a torch.
- FIG. 1 The Figure shows axially aligned optical fiber segments 1 and 2; torch 3 comprising an inner tube 31 with associated inlet 32 and an outer tube 33 with associated inlet 34; and flame 4 in the process of heating abutting ends of optical fiber segments 1 and 2.
- Torch 3 is preferably made from an inert, heat resistant material such as, e.g., fused silica.
- the invention is directed to flame processing of silica-based optical waveguide fibers for purposes such, e.g., fiber splicing, drawing, and coupling.
- silica-based optical waveguide fibers for purposes such, e.g., fiber splicing, drawing, and coupling.
- long lengths of silica-based optical waveguide fibers are made from two or more shorter lengths or segments, such manufacture involving flame fusion splicing of ends of fibers.
- the silica-based fibers preferably comprise an amount of silica of at least 90 mole percent of the total glass fiber material. Also, a preferred amount of at least 95 mole percent and preferably at least 98 mole percent of fiber surface material being heated is silica.
- Glass material is understood to extend to a depth of at least 10 micrometers and preferably at least 30 micrometers from a fiber mantle surface.
- Complementary percentages may be taken up by other glass constituents such as, e.g., dopant oxides.
- Fiber diameters of approximately 100-150 micrometers are typical, and a fiber core portion typically has a diameter of from a few micrometers in the case of single-mode fibers to approximately 50 micrometers in the case of multi-mode fibers.
- Optical fibers comprise a waveguiding core-cladding structure, the core portion having a refractive index which is greater than the refractive index of the surrounding cladding portion.
- Fibers intended for single-mode transmission typically have a stepped-index profile; in the case of multi-mode fibers a core-cladding structure preferably has a gradually changing refractive index profile.
- Raised refractive index of a core portion is conveniently achieved, e.g., by up-doping of silica with alumina, germania, or phosphorus pentoxide; conversely, boron or fluorine can be used for down-doping a silica cladding.
- dopants may be present for purposes other than waveguiding; e.g., small amounts of phosphorus pentoxide may be added to a cladding for the sake of lowering cladding glass softening temperature.
- Processing in accordance with the invention calls for flame heating at least a portion of at least one optical fiber or fiber segment at typical temperatures in a range of from 1200 degrees C to 2200 degrees C or, more typically, from 1500 degrees C to 2000 degrees C, such temperature being at or near the glass softening temperature.
- splicing two segments are heated which are essentially coaxially aligned and are brought into end-to-end contact.
- fiber segments may be aligned side-by-side or twisted together for fusing along the fiber periphery.
- Heating in accordance with the invention is by a flame produced by combustion in a flow of gases.
- Such flow comprises a central flow consisting essentially of a combustible gas selected from hydrogen, deuterium, ammonia, deuterated ammonia or a mixture thereof, and such flow further comprises a surrounding peripheral flow comprising primarily oxygen.
- the central flow comprises at least 50 and preferably at least 90 percent by volume of combustible gas
- the peripheral flow comprises at least 50 and preferably at least 90 volume percent oxygen.
- Contemplated primarily are complementary percentages of inert flow components such as, e.g., helium or nitrogen; and any appreciable amount of chlorine is excluded.
- the flame size (as visually ascertainable and as measured from the tip of a nozzle in the direction of gas flow) is in a range of from 0.5 to 10 mm and preferably from 1 to 5 mm.
- the fiber portion or portions being heated are preferably placed into the hottest part near the tip of the flame. Such placement may result in an abrupt exposure to elevated temperature; alternatively, allowance may be made for a gradual increase in fiber temperature, e.g., by gradually turning up a flame towards a placed fiber. Fibers are preferably centered across the flame front.
- aspects such as the small size of the flame, centered fiber placement, and the closeness of the fiber to the nozzle are considered to be beneficial in the interest of minimization of turbulence, uniformity of heat gradient and, ultimately, high strength of a spliced fiber.
- a strong flow of oxygen be maintained immediately adjacent to and surrounding the flow of combustible gas; such flow is required to have sufficiently high volume as well as sufficiently high velocity.
- Preferred flows are significantly greater than flows needed to sustain a flame, and the velocities are in a range of from 0.3 to 10 m/sec and preferably in a range of from 0.5 to 5 m/sec.
- Contemplated volume of flow adjacent to the flame is a function of the radial thickness of such flow, such thickness being greater than or equal to 0.1 mm as produced, e.g., by one or several concentric orifices of a torch nozzle.
- oxygen flow is believed to contribute to high-strength splice connections by a number of mechanisms such as, in particular, cooling of fiber portions adjacent to portions exposed to the ambient, shielding of heated fiber portions from ambient moisture, and removal of water-derived species such as, e.g., OH- and H 2 0 reaction products from the vicinity of the heated fiber. (Too high a flow rate of oxygen is precluded, however, in the interest of adequate heating of a fiber portion and also in the interest of avoiding excessive turbulence.)
- Optical loss introduced into the resulting fiber waveguides by the presence of a splice connection optimally was as low as approximately 0.05 dB, values of up to 0.1 dB being considered as good and values up to 0.2 dB being considered as acceptable. Indeed, such levels were easily met concomitant to accurate alignment of fiber segment ends, and primary concern is with spliced fiber strength.
- Example I Forty-one splice connections were made by flame fusing optical fiber segments having a nominal waveguide structure as follows: Silica core glass doped germania for increased refractive index, silica cladding glass doped with fluorine for decreased refractive index and also doped lightly with phosphorus pentoxide for lowered glass softening temperature, essentially pure silica surrounding the cladding and forming the fiber surface, core diameter of approximately 10 micrometers, over-all fiber diameter approximately 125 micrometers.
- Heating was by means of a three-orifice torch analogous to the two-orifice torch depicted in the Figure, and approximate nozzle dimensions were as follows: A central orifice radius of 0.125 mm, a first wall thickness of 0.8 mm, an intermediate-orifice gap of 0.25 mm, a second wall thickness of 0.8 mm, an outer-orifice gap of 0.125 mm, and a third wall thickness of 0.8 mm.
- Flow to the central orifice was essentially pure hydrogen which at first was adjusted merely sufficient to maintain a flame.
- Flow to the intermediate as well as to the outer orifices was approximately 0.6 I/min oxygen, resulting in a combined flow of approximately 1.2 Vmin at a velocity of approximately 1.5 m/sec and having a radial thickness of approximately 1.6 mm.
- Fiber ends were aligned and brought into physical contact, and the joined fibers were placed in front of the oxygen-hydrogen flame which was then adjusted to a visual size of approximately 3 mm by increasing the hydrogen flow. Fusing of the joined fiber ends was at temperatures in a range of from approximately 1800 degrees C to approximately 1900 degrees C; fusion times ranged from approximately I to approximately 40 seconds, shorter times being associated with higher temperatures and conversely.
- the mean strength of the spliced fibers was approximately 706 kpsi (6.87 GPa) with a coefficient of variation of approximately 0.103. Forty or approximately 97 percent of the resulting spliced fibers had a strength greater than 500 kpsi (3.45 GPa).
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Geochemistry & Mineralogy (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Life Sciences & Earth Sciences (AREA)
- Plasma & Fusion (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Mechanical Coupling Of Light Guides (AREA)
Description
- The invention is concerned with optical waveguide glass fibers having low optical loss and high tensile strength as, e.g., in the case of fibers having a low-loss, high-strength splice connection.
- Optical waveguide glass fibers have become an increasingly important long-distance communications medium, and their commercial use for communications over intermediate and short distances is increasing as well. Manufacture of optical waveguide fibers typically is by drawing from a preform as may be made in a number of ways; in this respect see, e.g., U. S. Patent 4,217,027. For the sake of mechanical protection, drawn fibers typically are provided with a plastic coating, and coated fibers may be assembled into strands and cables.
- In the construction of long-distance communications facilities, special attention is due the optical and physical interconnection of lengths of fiber. In this respect, heat fusion splicing has been developed as reported, e.g., by J. T. Krause et al., "Tensile Strengths > 4 GPa for Light Guide Fusion Splices", Electronics Letters, Vol. 17 (1981), pp. 812-813. There, the choice of processing conditions is strongly influenced by considerations of tensile strength of a resulting spliced fiber, this in view of considerable tensile forces as may be applied in the course of cable installation, e.g., by pulling through ducts or by laying at sea.
- Heat fusion splicing typically involves the use of a torch producing a flame which results upon the combustion of gases such as, e.g., hydrogen or ammonia. And, of course, such a flame can be used for high-temperature processing for purposes other than splicing. For example, flame processing can be used to facilitate drawing of a fiber to a smaller diameter, for side-by-side fusing of fibers as, e.g., in the manufacture of optical couplers and taps, as well as for the sake of modifying dopant profile. With respect to dopant profile modification see, e.g., J.T. Krause et al., "Splice Loss of Single-mode Fiber as Related to Fusion Time, Temperature, and Index Profile Alteration", IOOC-ECOC 185 Technical Digest. Vol. 1, Istituto Internazionale delle Comu- nicazioni, 1985; pp. 629-631. And, with respect to diameter reduction, see, e.g., U.S. Patent 3 825 319.
- EP-150 095 discloses flame processing with chlorine addition to result in highest tensile strength in a processed fiber, but there remain circumstances under which the use of chlorine is inadvisable, e.g., on the basis of safety or environmental considerations.
- The problem underlying the present invention is to provide for a method for making a glass fiber in accordance with the pre-characterizing part of claim 1 which is improved in regard of safety and environmental considerations.
- This problem is solved in accordance with the teachings of claim 1.
- Resulting fibers have satisfactorily high tensile strength for most applications; for example, if processing is for the sake of fiber splicing, at least 80 percent of fibers spliced in accordance with the invention have a tensile strength greater than or equal to 3.45 GPa (500 kpsi).
- The Figure schematically illustrates a preferred embodiment of the invention, namely fiber splicing by heating of abutting fiber segment ends with a torch.
- The Figure shows axially aligned optical fiber segments 1 and 2; torch 3 comprising an
inner tube 31 with associated inlet 32 and anouter tube 33 with associated inlet 34; and flame 4 in the process of heating abutting ends of optical fiber segments 1 and 2. Torch 3 is preferably made from an inert, heat resistant material such as, e.g., fused silica. - The invention is directed to flame processing of silica-based optical waveguide fibers for purposes such, e.g., fiber splicing, drawing, and coupling. For example, in the case of splicing, long lengths of silica-based optical waveguide fibers are made from two or more shorter lengths or segments, such manufacture involving flame fusion splicing of ends of fibers. The silica-based fibers preferably comprise an amount of silica of at least 90 mole percent of the total glass fiber material. Also, a preferred amount of at least 95 mole percent and preferably at least 98 mole percent of fiber surface material being heated is silica. (Surface material is understood to extend to a depth of at least 10 micrometers and preferably at least 30 micrometers from a fiber mantle surface.) Complementary percentages may be taken up by other glass constituents such as, e.g., dopant oxides.
- Fiber diameters of approximately 100-150 micrometers are typical, and a fiber core portion typically has a diameter of from a few micrometers in the case of single-mode fibers to approximately 50 micrometers in the case of multi-mode fibers.
- Optical fibers comprise a waveguiding core-cladding structure, the core portion having a refractive index which is greater than the refractive index of the surrounding cladding portion. Fibers intended for single-mode transmission typically have a stepped-index profile; in the case of multi-mode fibers a core-cladding structure preferably has a gradually changing refractive index profile. Raised refractive index of a core portion is conveniently achieved, e.g., by up-doping of silica with alumina, germania, or phosphorus pentoxide; conversely, boron or fluorine can be used for down-doping a silica cladding. Furthermore, dopants may be present for purposes other than waveguiding; e.g., small amounts of phosphorus pentoxide may be added to a cladding for the sake of lowering cladding glass softening temperature.
- Processing in accordance with the invention calls for flame heating at least a portion of at least one optical fiber or fiber segment at typical temperatures in a range of from 1200 degrees C to 2200 degrees C or, more typically, from 1500 degrees C to 2000 degrees C, such temperature being at or near the glass softening temperature. For example, in the case of splicing, two segments are heated which are essentially coaxially aligned and are brought into end-to-end contact. Or, in the case of the manufacture of a coupler, fiber segments may be aligned side-by-side or twisted together for fusing along the fiber periphery.
- Heating in accordance with the invention is by a flame produced by combustion in a flow of gases. Such flow comprises a central flow consisting essentially of a combustible gas selected from hydrogen, deuterium, ammonia, deuterated ammonia or a mixture thereof, and such flow further comprises a surrounding peripheral flow comprising primarily oxygen. The central flow comprises at least 50 and preferably at least 90 percent by volume of combustible gas, and the peripheral flow comprises at least 50 and preferably at least 90 volume percent oxygen. Contemplated primarily are complementary percentages of inert flow components such as, e.g., helium or nitrogen; and any appreciable amount of chlorine is excluded.
- The flame size (as visually ascertainable and as measured from the tip of a nozzle in the direction of gas flow) is in a range of from 0.5 to 10 mm and preferably from 1 to 5 mm. The fiber portion or portions being heated are preferably placed into the hottest part near the tip of the flame. Such placement may result in an abrupt exposure to elevated temperature; alternatively, allowance may be made for a gradual increase in fiber temperature, e.g., by gradually turning up a flame towards a placed fiber. Fibers are preferably centered across the flame front. Aspects such as the small size of the flame, centered fiber placement, and the closeness of the fiber to the nozzle are considered to be beneficial in the interest of minimization of turbulence, uniformity of heat gradient and, ultimately, high strength of a spliced fiber.
- Moreover, in accordance with the invention, it is particularly important that a strong flow of oxygen be maintained immediately adjacent to and surrounding the flow of combustible gas; such flow is required to have sufficiently high volume as well as sufficiently high velocity. Preferred flows are significantly greater than flows needed to sustain a flame, and the velocities are in a range of from 0.3 to 10 m/sec and preferably in a range of from 0.5 to 5 m/sec. Contemplated volume of flow adjacent to the flame is a function of the radial thickness of such flow, such thickness being greater than or equal to 0.1 mm as produced, e.g., by one or several concentric orifices of a torch nozzle. Use of such oxygen flow is believed to contribute to high-strength splice connections by a number of mechanisms such as, in particular, cooling of fiber portions adjacent to portions exposed to the ambient, shielding of heated fiber portions from ambient moisture, and removal of water-derived species such as, e.g., OH- and H20 reaction products from the vicinity of the heated fiber. (Too high a flow rate of oxygen is precluded, however, in the interest of adequate heating of a fiber portion and also in the interest of avoiding excessive turbulence.)
- The following examples illustrate the effectiveness of the disclosed flame processing method as exemplified in the case of fiber splicing. Optical loss introduced into the resulting fiber waveguides by the presence of a splice connection optimally was as low as approximately 0.05 dB, values of up to 0.1 dB being considered as good and values up to 0.2 dB being considered as acceptable. Indeed, such levels were easily met concomitant to accurate alignment of fiber segment ends, and primary concern is with spliced fiber strength.
- As can be seen from the examples, desirable levels of tensile strength at or above 500 kpsi (3.45 GPa) are readily achieved in the case of fibers made in accordance with the invention; accordingly, such fibers are suitable for incorporation in optical fiber cables as typically comprising a significant number of five or more fibers. For the sake of comparison, and in contradistinction to the invention, thirty-nine splice connections were made by prior art flame fusion splicing using a slow flow of oxygen and a relatively large flame. Only two of the resulting 39 spliced fibers had acceptable strength of approximately 500 kpsi (3.45 GPa).
- Example I. Forty-one splice connections were made by flame fusing optical fiber segments having a nominal waveguide structure as follows: Silica core glass doped germania for increased refractive index, silica cladding glass doped with fluorine for decreased refractive index and also doped lightly with phosphorus pentoxide for lowered glass softening temperature, essentially pure silica surrounding the cladding and forming the fiber surface, core diameter of approximately 10 micrometers, over-all fiber diameter approximately 125 micrometers.
- Heating was by means of a three-orifice torch analogous to the two-orifice torch depicted in the Figure, and approximate nozzle dimensions were as follows: A central orifice radius of 0.125 mm, a first wall thickness of 0.8 mm, an intermediate-orifice gap of 0.25 mm, a second wall thickness of 0.8 mm, an outer-orifice gap of 0.125 mm, and a third wall thickness of 0.8 mm. Flow to the central orifice was essentially pure hydrogen which at first was adjusted merely sufficient to maintain a flame. Flow to the intermediate as well as to the outer orifices was approximately 0.6 I/min oxygen, resulting in a combined flow of approximately 1.2 Vmin at a velocity of approximately 1.5 m/sec and having a radial thickness of approximately 1.6 mm. Fiber ends were aligned and brought into physical contact, and the joined fibers were placed in front of the oxygen-hydrogen flame which was then adjusted to a visual size of approximately 3 mm by increasing the hydrogen flow. Fusing of the joined fiber ends was at temperatures in a range of from approximately 1800 degrees C to approximately 1900 degrees C; fusion times ranged from approximately I to approximately 40 seconds, shorter times being associated with higher temperatures and conversely. The mean strength of the spliced fibers was approximately 706 kpsi (6.87 GPa) with a coefficient of variation of approximately 0.103. Forty or approximately 97 percent of the resulting spliced fibers had a strength greater than 500 kpsi (3.45 GPa).
- Exampie 2. Thirty-one splice connections were made under conditions as described above in Example I, with the exception that there was no gradual turning-up of the flame; instead, joined fiber ends were exposed abruptly to a nominal-size flame. The mean strength of the spliced fibers was approximately 671 kpsi (4.63 GPa) with a coefficient of variation of approximately 0.156. Twenty-eight or approximately 90 percent of the resulting spliced fibers had a strength greater than 500 kpsi (3.45 GPa).
Claims (12)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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US06/829,527 US4689065A (en) | 1986-02-14 | 1986-02-14 | Optical waveguide glass fiber flame processing |
US829527 | 1986-02-14 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0232918A1 EP0232918A1 (en) | 1987-08-19 |
EP0232918B1 true EP0232918B1 (en) | 1990-09-19 |
Family
ID=25254785
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP87102086A Expired EP0232918B1 (en) | 1986-02-14 | 1987-02-13 | Optical waveguide glass fiber flame processing |
Country Status (5)
Country | Link |
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US (1) | US4689065A (en) |
EP (1) | EP0232918B1 (en) |
JP (1) | JPS62192706A (en) |
CA (1) | CA1274695A (en) |
DE (1) | DE3764966D1 (en) |
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JPS6045207A (en) * | 1983-08-22 | 1985-03-11 | Fujikura Ltd | Method for connecting optical fiber |
US4557556A (en) * | 1983-10-28 | 1985-12-10 | At&T Bell Laboratories | Method of fabricating an optical attenuator by fusion splicing of optical fibers |
US4557557A (en) * | 1983-10-28 | 1985-12-10 | At&T Bell Laboratories | Method of making an optical fiber attenuator using a lossy fusion splice |
EP0169237A1 (en) * | 1984-01-24 | 1986-01-29 | AT&T Corp. | Glass fiber splicing by flame fusion |
-
1986
- 1986-02-14 US US06/829,527 patent/US4689065A/en not_active Expired - Lifetime
-
1987
- 1987-01-27 CA CA000528293A patent/CA1274695A/en not_active Expired - Fee Related
- 1987-02-13 DE DE8787102086T patent/DE3764966D1/en not_active Expired - Fee Related
- 1987-02-13 EP EP87102086A patent/EP0232918B1/en not_active Expired
- 1987-02-13 JP JP62029937A patent/JPS62192706A/en active Granted
Also Published As
Publication number | Publication date |
---|---|
JPH0524484B2 (en) | 1993-04-08 |
CA1274695A (en) | 1990-10-02 |
US4689065A (en) | 1987-08-25 |
EP0232918A1 (en) | 1987-08-19 |
JPS62192706A (en) | 1987-08-24 |
DE3764966D1 (en) | 1990-10-25 |
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